In dynamic nuclear polarisation (DNP) experiments performed under static conditions at 1.4 K we show that the presence of 1 mM Gd(iii)-DOTAREM increases the (13)C polarisation and decreases the (13)C polarisation buildup time of (13)C-urea dissolved in samples containing water/DMSO mixtures with trityl radical (OX063) concentrations of 10 mM or higher. To account for these observations further measurements were carried out at 6.5 K, using a combined EPR and NMR spectrometer. At this temperature, frequency swept DNP spectra of samples with 5 or 10 mM OX063 were measured, with and without 1 mM Gd-DOTA, and again a (13)C enhancement gain was observed due to the presence of Gd-DOTA. These measurements were complemented by electron-electron double resonance (ELDOR) measurements to quantitate the effect of electron spectral diffusion (eSD) on the DNP enhancements and lineshapes. Simulations of the ELDOR spectra were done using the following parameters: (i) a parameter defining the rate of the eSD process, (ii) an "effective electron-proton anisotropic hyperfine interaction parameter", and (iii) the transverse electron spin relaxation time of OX063. These parameters, together with the longitudinal electron spin relaxation time, measured by EPR, were used to calculate the frequency profile of electron polarisation. This, in turn, was used to calculate two basic solid effect (SE) and indirect cross effect (iCE) DNP spectra. A properly weighted combination of these two normalized DNP spectra provided a very good fit of the experimental DNP spectra. The best fit simulation parameters reveal that the addition of Gd(iii)-DOTA causes an increase in both the SE and the iCE contributions by similar amounts, and that the increase in the overall DNP enhancements is a result of narrowing of the ELDOR spectra (increased electron polarisation gradient across the EPR line). These changes in the electron depolarisation profile are a combined result of shortening of the longitudinal and transverse electron spin relaxation times, as well as an increase in the eSD rate and in the effective electron-proton anisotropic hyperfine interaction parameter.
Efficient Dynamic Nuclear Polarization at 800 MHz/527 GHz with Trityl-Nitroxide Biradicals
From The DNP-NMR Blog:
Efficient Dynamic Nuclear Polarization at 800 MHz/527 GHz with Trityl-Nitroxide Biradicals
Mathies, G., et al., Efficient Dynamic Nuclear Polarization at 800 MHz/527 GHz with Trityl-Nitroxide Biradicals. Angew Chem Int Ed Engl, 2015: p. n/a-n/a.
http://www.ncbi.nlm.nih.gov/pubmed/26268156
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08-31-2015 09:39 PM
Self-assembled trityl radical capsules--implications for dynamic nuclear polarization
From The DNP-NMR Blog:
Self-assembled trityl radical capsules--implications for dynamic nuclear polarization
Marin-Montesinos, I., et al., Self-assembled trityl radical capsules--implications for dynamic nuclear polarization. Phys Chem Chem Phys, 2015. 17(8): p. 5785-94.
http://www.ncbi.nlm.nih.gov/pubmed/25626422
Dynamic nuclear polarisation NMR of nanosized zirconium phosphate polymer fillers
From The DNP-NMR Blog:
Dynamic nuclear polarisation NMR of nanosized zirconium phosphate polymer fillers
Ziarelli, F., et al., Dynamic nuclear polarisation NMR of nanosized zirconium phosphate polymer fillers. Chemical Communications, 2014. 50(70): p. 10137-10139.
http://dx.doi.org/10.1039/C4CC02723J
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08-09-2014 05:20 AM
Static (1)H dynamic nuclear polarization with the biradical TOTAPOL: a transition between the solid effect and the cross effect
From The DNP-NMR Blog:
Static (1)H dynamic nuclear polarization with the biradical TOTAPOL: a transition between the solid effect and the cross effect
Shimon, D., et al., Static (1)H dynamic nuclear polarization with the biradical TOTAPOL: a transition between the solid effect and the cross effect. Phys Chem Chem Phys, 2014. 16(14): p. 6687-99.
http://www.ncbi.nlm.nih.gov/pubmed/24585094
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06-04-2014 03:22 PM
Dynamic nuclear polarisation enhanced 14N overtone MAS NMR spectroscopy
From The DNP-NMR Blog:
Dynamic nuclear polarisation enhanced 14N overtone MAS NMR spectroscopy
Rossini, A., L. Emsley, and L.A. O'Dell, Dynamic nuclear polarisation enhanced 14N overtone MAS NMR spectroscopy. Phys. Chem. Chem. Phys., 2014.
http://dx.doi.org/10.1039/C4CP00590B
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05-16-2014 08:06 PM
The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals
From The DNP-NMR Blog:
The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals
Banerjee, D., et al., The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals. J. Magn. Reson., 2013. 230(0): p. 212-219.
http://dx.doi.org/10.1016/j.jmr.2013.02.010
The effect of Gd on trityl-based dynamic nuclear polarisation in solids
Linear Mode
